Jan Industry Note: Diagnostic Testing of Influenza 

South Carolina Blues had reviewed and published the policy on Influenza testing. 

Description
Influenza is an acute respiratory illness caused by influenza A or B viruses resulting in upper and lower respiratory tract infection, fever, malaise, headache, and weakness. It mainly occurs in outbreaks and epidemics during the winter season, and is associated with increased morbidity and mortality in certain high-risk populations (Dolin, 2024b). 

Rapid influenza diagnostic tests (RIDTs) refer to clinical laboratory improvement amendments (CLIA) waived immunoassays that can detect influenza viruses during the outpatient visit, giving results in a clinically relevant time period to inform treatment decisions (CDC, 2017). Besides RIDTs, influenza can be detected using polymerase chain reaction (PCR)-based assays as well as culture testing; however, the former is not often used in initial clinical management due to time constraints. Serologic testing is not used in outpatient settings for diagnosis (Dolin, 2024a). 

Policy
Application of coverage criteria is dependent upon an individual’s benefit coverage at the time of the request.   

1. For symptomatic individuals (see Note 1), one (see Note 2), but not both, of the following is considered MEDICALLY NECESSARY: 
   • One single rapid flu test (either a point-of-care rapid nucleic acid amplification test (NAAT) or a rapid antigen test). 
   • One single traditional NAAT. 
2. Viral culture testing for influenza in an outpatient setting is considered NOT MEDICALLY NECESSARY. 
3. In asymptomatic patients, outpatient influenza testing, including rapid antigen flu tests, rapid NAAT or RT-PCR tests, traditional RT-PCR tests, and viral culture testing, is considered NOT MEDICALLY NECESSARY. 
4. Serology testing for influenza is considered NOT MEDICALLY NECESSARY under any circumstance. 

Note 1: Typical Influenza Signs and Symptoms.3   

• Fever or feeling feverish/chills 
• Cough 
• Sore throat 
• Headaches 
• Muscle or body aches 
• Fatigue 
• Runny or stuffy nose 
• Vomiting and/or diarrhea (more common in children than adults) 

Note 2: One influenza test may detect influenza A and/or influenza B. When both influenza A and influenza B are detected by a test represented by CPT codes 87400, 87501, or 87804, up to two units may be billed at a single visit.